I am friends with a hetrosexual couple who have been together for the last six years and now live together. They are early/mid thirties
The man has always been clear he doesn't want children. Probably not clear enough when you take into account that having children is the "usual" setting and people assume that you will change your mind when you get older, but clear nonetheless.
The woman has always wanted marriage and children. She assumed that he would come around on the basis that most men in their late 20s don't go around talking about having children but most do later. (I am paraphrasing her view). Over the last year, she has been dropping increasingly heavy hints.
A couple of nights ago she made a joke about "helping" him along with an "accidental" pregnancy. (I don't know exactly what she said as I wasn't there).
The man reacted very badly. He told her that he unequivocally didn't want children, would not sleep with her without a condom as well as proof of another contraceptive and that if she did become pregnant he would provide no more support than the bare financial minimum.
Woman walked out, because she can't stay with a man who doesn't trust her, and is sleeping in my spare room.
Obviously this is none of my business, and I've seen enough break ups to keep my views to myself, but I'm interested who you think is BU. I think woman is - but then I have very strong views about tricking a man into getting you pregnant, and I've seen a scenario where it didn't end well (seperation, abortion). DH thinks man is BU because he should have spelled out that "I don't want children" means "never ever ever" a long time ago.